1. Field of the Invention
This invention relates to air standard engines and, more particularly, to an air standard engine apparatus and method, wherein pressurized air to drive an expansion engine is compressed generally isothermally within a refrigerant-cooled compressor/heat exchanger and the resulting high pressure air is stored at ambient temperature to be utilized in the expansion engine to produce mechanical energy after which the air is recycled to the compressor.
2. The Prior Art
Historically, the utilization of chemical energy stored within fossil fuels such as gasoline, diesel fuel, or the like, is accomplished by converting the chemical energy to thermal energy either in an internal or an external combustion engine with the engine converting the thermal energy to mechanical energy in a rotating shaft. The mechanical energy is then utilized directly through the use of transmissions, generators, pulleys, and the like. Therefore, the amount of mechanical energy produced for a particular function is controlled by the amount of thermal energy and, therefore, the amount of fuel consumed in the internal or external combustion engine, accounting for losses and inefficiencies. Accordingly, each engine is designed with a view toward the maximum power output requirements for that particular engine application even though the average work load may be substantially smaller. As a result, the engine is usually over-designed for the particular work requirements with a corresponding waste in fuel consumption during the extended periods of lower power requirements. In recognition of this problem, various energy storage devices have been proposed and include, for example, high-speed flywheels, batteries, air storage tanks, and the like. While air storage tanks present certain advantages, particularly since the storage medium (air) is plentiful, relatively safe, and the capital expenditure for air storage systems is relatively low, the disadvantages are in the various heat losses, particularly the heat of compression, that are incurred. The heat losses represent a lowering of the overall efficiency of the system and, where the heat is retained, an additional work load for the compressor to compress a given volume of air to a given pressure.
In view of the foregoing, it would be an advancement in the art to provide an air standard engine whereby air is compressed and held in a storage reservoir for subsequent expansion and recovery of energy therefrom through an expansion engine, the compression of the air being accomplished at a relatively low temperature by means of a refrigeration system removing thermal energy from the air. It would also be an advancement in the art to provide an air compressor apparatus wherein a refrigerant absorbs thermal energy from the air and at least a portion of that energy is used to increase pressure within the refrigerant to thereby assist in compressing the air. It would also be an advancement in the art to utilize a portion of the compressed air to recover heat from a combustion engine and use the heated air as the combustion air. Such an apparatus and method is disclosed and claimed herein.